Diuretics Flashcards
What are 3 primary functions of the kidney?
- Maintain fluid balance
- Filters metabolic wastes and water
- Regulates blood volume, electrolytes, and acid-base balance
What are 3 secondary functions of the kidney?
- Secrete erythropoietin (signal = reduction in o2 to kidney)
- Secrete renin (regulates BP by causing vasoconstriction, and starts RAAS system cascade)
- Activate calcitriol (goal = increase Ca+ or Phos)
Anatomy of Kidney
Renal cortex = outer
Renal medulla = middle layer
Nephron = within the renal pyramid of the renal medulla that is the functional unit of the kidney
Nephron
2 inces long
1,000,000 within each kidney
Functional unit
Blood supply from afferent
Nephron Anatomy
Afferent = toward, efferent = away, arterioles Glomerulus = filter Filtrate = filtered fluid through Bowman's capsule Proximal convoluted tubule Descending loop of Henle Ascending loop of Henle Distal convoluted tubule Collecting duct
Filtrate
- Filtered fluid through Bowman’s capsule
- Enters convoluted tubule
- Reabsorbed at Loop of Henle
- Exits collecting duct
What are the 3 changes to filtrate?
- Reabsorption - substances move across tubule wall through interstitial fluid and enters blood at the peritubular capillary. Q 180L passing through, 178L is reabsorbed. (Na+, K+, Bicarbonate, water)
- Secretion - Away from peritublar capillary to renal tubule (H+, phosphate, ammonia)
- Excretion - Down tubule toward bladder (see video)
What is the purpose of diuretics?
Remove water/electrolytes from the body
Tx: edema, HTN, etc.
What are the 5 classes of diuretics?
- Loop diuretics
- Thiazide diuretics
- Potassium-sparing diruetics
- Osmotic diuretics
- Carbonic Anhydrase Inhibitors (CAIs)
How do loop of Diuretics work and what is an example drug?
Blocks reabsorption of Na+, Cl-, H2O in acending loop of Henle.
Ex: Furosemide - inhibits reabsorption of Na+ & Cl-, increases diuresis, excretion of K+ (adverse effect)
When would you give loop diuretics?
Tx: edema, manage HTN
What are 4 adverse effects of loop diuretics?
- Dehydration/electrolyte imbalances
- Hypotension
- Hypokalemia
- Hyperglycemia - insulin secretion decreases
How do thiazide diuretics work and an example drug? (4)
- Acts on distal convoluted tubule
- Blocks reabsorption of Na+, Cl-, K+
- Reduces preload/afterload - relaxes arterioles - ventricle pressure, reduces stretch of heart
- Reduces peripheral vascular resistance - relaxes arterioles
Example: Hydrochlorothiazide (HCTZ)
When would you give thiazide diuretics?
Tx: mild to moderate HTN, management of edema r/t HF and renal dz
What are 3 adverse effects of thiazide diuretics?
- Hypokalemia
- Hyperglycemia
- Hypotension
How is aldosterone activated?
Released by adrenal gland.
Stimulated by RAAS system via angiotensin II or kidneys sense low Na+/BP or high K+
What are the functions of aldosterone?
- Increases retention of Na+
- Excretion of K+ via urine
- Increase blood volume
- Increase BP
Where does aldosterone bind?
Binds to tubular cells in the convoluted tubule and collecting duct
What is the function of potassium-sparing diuretics and an example?
Aldosterone-antagonist - excretes Na+ and H2O; retains K+
Example: spironolactone
Why would you use potassium-sparing diuretics?
Management of HTN and edema
Counteracts K+ loss caused by other diuretics
What is an adverse effect of potassium-sparing diuretics?
Hyperkalemia
What are 4 functions of osmotic diuretics and an example drug?
- Increases osmotic pressure of filtrate
- Pulls H2O into renal tubules
- Acts on proximal tubule and descending limb
- Produces rapid diuresis
Ex: Mannitol
Why would you give osmotic diuretics?
Reduce intracranial pressure
What is an adverse effect of osmotic diuretics?
Dehydration
What is carbonic anhydrase (CA)?
An enzyme that helps us regulate acid-base balance
What are 3 functions of carbonic anhydrase (CA)?
- Forms the aqueous humor
- H+ ions needed for transport of Na+ and H2O
- Formation of HCO3- (changes CO2 and H2O)
What are 4 functions of carbonic anhydrase inhibitors (CAIs) and an example drug?
- Reduces formation of H+ ions and HCO3- ions.
- Effect in proximal convoluted tubule
- Inhibits CA
- Prevents Na+ and H2O reabsorption
Example: Acetazolamide (Diamox)
Why would you use CAIs?
Tx: Intraocular pressure (glaucoma) and prevent or treat altitude sickness (tachapnea). Limited use in HTN/HF due to AE
What is an adverse effect of CAIs?
Metabolic acidosis due to lack of HCO3-
What are 6 diuretic effects on geriatric patients?
- Encourage AM dose
- Can cause dizziness, lightheadedness
- Increase risk of falls
- Risk of orthostatic hypotension
- Lower doses if taking other diuretics or anti-HTN
- More prone to F&E imbalances
What are nursing implications?
D.I.U.R.E.T.I.C
D = diet (monitor K+) I = I/O monitoring, daily wt (HF pts) U = unbalanced F&E (labs) R = ready for dynamic changes in BP, HR E = no evening doses (increases risk of falls - nocturia) T = take in AM I = increased risk for orthostatic hypotension C = conditions, age, or drugs resulting in F&E imbalances
NANDAs
Deficient fluid volume
Deficient knowledge (diuretic therapy)
Risk for falls r/t hypotension and dizziness associated with adverse drug effects
Risk for injury r/t hypotension and dizziness associated with adverse drug effects
Risk for urge urinary incontinence
